A fusible link conventionally is used in those instances in which it is desired that some mechanism operate automatically, but not until there is an increase in temperature such as that resulting from a fire. Mechanisms of the kind adapted for such automatic operation include fire door closing apparatus, sprinkler operating units, alarm systems, and the like. Conventionally, a fusible link is interposed between relatively movable members which are restrained from movement by a temperature sensitive strut until such time as its temperature increases to a predetermined level, whereupon the link collapses and becomes ineffective to prevent relative movement between such members.
Numerous kinds of fusible links have been proposed heretofore, two of which are disclosed in U.S. Pat. Nos. 3,779,004 and 4,346,554. Although such fusible links are reliable, they require multiple parts, rely upon moment arms, and are relatively expensive to manufacture and assemble compared to a link according to the present invention.